1. Field of the Invention
The present invention relates to a signal input/output apparatus. In particular, the present invention relates to a signal input/output apparatus which is provided with at least one signal input section for sending an input signal from a sensor, a switch or the like to a programmable controller by means of serial transmission and/or at least one signal output section for sending an output signal from the programmable controller to a solenoid-operated valve manifold or the like by means of parallel transmission, wherein a number of the signal input sections and the signal output sections can be changed so as not to require wiring.
2. Description of the Related Art
The conventional signal input/output apparatus comprises a signal input section and a signal output section for performing serial transmission of a signal from an input apparatus such as a sensor and a switch carried on a cylinder or an output apparatus such as a solenoid-operated valve manifold and an indicator lamp to a control unit such as a programmable controller. Respective connectors of the signal input section and the signal output section of the signal input/output apparatus is integrally arranged with a main body. Accordingly, it has been impossible to divide the signal input section and the signal output section from the main body.
With the conventional signal input/output apparatus, a control system must be large in its entirety and a space for installing the control system is increased if a sensor, a solenoid-operated valve manifold or the like to be carried on the cylinder is added because it is necessary to provide another signal input section or another signal output section. In addition, complicated wiring for the signal input section, the signal output section, and the programmable controller requires a lot of labor to maintain and inspect the signal input/output apparatus, the programmable controller or the like.
It is a general object of the present invention to provide a signal input/output apparatus which can change a number of signal input sections and signal output sections that are integrated into one unit and which can easily change a number of input apparatuses such as sensors and switches carried on a cylinder and output apparatuses such as solenoid-operated valve manifolds and indicator lamps.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.